Acute coronary syndromes (ACS), characterized by either acute myocardial infarction (MI) or unstable angina, are most commonly precipitated by plaque rupture, which accounts for about 60-75% of fatal acute myocardial infarctions and/or sudden coronary deaths. The ruptured atherosclerotic plaques occur on a background of underlying atherosclerotic disease. Alarmingly, in patients presenting ACS, the recurrent cardiovascular event rate is high over the next two years, even with good medical management. The one year incidence of cardiovascular death, nonfatal MI, readmission for ACS and stroke is 8-12% during one year follow-up and 11-14% during two years follow-up.
This high rate of recurrent cardiovascular events, despite aggressive therapy, may be due to the now commonly held belief that ACS has a systemic inflammatory component, one manifestation of which is that many ACS patients have several vulnerable plaques in addition to the ruptured culprit lesion responsible for precipitating the ACS. The risk of rupture over the succeeding months posed by these additional vulnerable plaques accounts, in large part, for the high recurrence rate of cardiovascular events. While atherosclerotic plaques can be severe enough so that they compromise flow and therefore result in warning symptoms, they may be mild and not cause any warning symptoms. However, atherosclerotic plaques might still rupture and produce catastrophic clinical consequences.
Plaque rupture also plays an important role in stroke with the culprit lesions in these patients lying usually in the carotid artery.